Molluscs are cold-blooded, they do not produce heat themselves and they adapt to their surrouding an take on the same temperature as their environment. They protect themselves against environmental influences, such as changes in salinity, humidity and temperature by creating a layer of slime. That is why a snail feels cold and slimy when you touch it.
Because molluscs are not considered 'cuddly', we know much less about them compared to other animals. The fact is that they are declining considerably in numbers and types.